The present invention relates generally to processing of data packets pursuant to communication protocols and, more particularly, to processing of data packets for a precision timing protocol.
It may be advantageous for devices in a communication network to utilize a common time base. The common time base may be used, for example, to trigger coordinated events in a network of sensors or to coordinate actions of controllers in an industrial system. In addition to sensors and controllers, the system may include computers and communication devices, such as routers.
The electronics industry has developed several standard protocols for use in synchronizing clocks, for example, the OAM functions and mechanisms of ITU-T Recommendation Y.1731 and the Precision Time Protocol (PTP) of IEEE standard 1588. The timing protocols may include sending timing-related messages between nodes in a communication network. The timing-related messages may include, for example, a node transmitting a time-stamped packet to supply its timebase to another node and a node transmitting a packet requesting the receiving node to reply with the time of receipt. Unfortunately, the use of possibly multiple timing related protocols may present difficulties.
In addition, the timing-related messages may be communicated using one or more protocols. Information in communication networks is formatted according to communication protocols. Communication protocols are commonly described in published standards. Many communication networks send and receive the information in packets. The communication protocols specify where various pieces of information are placed in the packets. For example, an identifier of the sender of the packet, an identifier of the intended recipient of the packet, and the message to be communicated may be placed in the packet in three locations defined by the communication protocol.
Unfortunately, each communication protocol may establish its own unique definition of where the various pieces of information are placed within a packet. Moreover, a communication network may use multiple protocols. Furthermore, multiple protocols may be used in sending one packet with a packet formatted according to a first protocol encapsulated in a packet formatted according to a second protocol, which is encapsulated in a packet formatted according to a third protocol, and so on. In addition, some network devices may process some packets which do require timing related actions and some packets which do not.